As is commonly understood by those practiced in the art of electrical generator design, the capacity of current machines for power generation is constrained by physical size, which is to be minimized in order to also minimize cost. Designers are further cognizant of size and weight limitations imposed by domestic and foreign ground transportation systems.
It is also commonly understood that magnetic and resistive losses within the stator generate heat which must be dissipated in order to avoid electro-mechanical failure, and that these losses pose a serious constraint on the capacity of a machine of given physical dimension. The high thermal capacity and thermal conductivity of gaseous hydrogen have been successfully exploited in the past by manufacturers seeking to satisfy customer's needs for increased capacity, within the constraints of physical shipping envelope and thermal loading. For those customers who are unwilling to suffer the additional cost and complexity of hydrogen cooling, manufacturers must devise the means to manage increases in thermal loading that accompany their efforts to coax additional capacity from machines of a given physical dimension.
The current state of the art is typified by a radial duct formed by separating stator core laminations by radially arranged inside spacer blocks, as shown in FIG. 1 and as described further below. Gaseous fluid flow is encouraged to progress in a radially-inward direction from a plenum area posterior to the stator core to the rotor/stator air gap (a radially-outward flow direction is also possible). These radial ducts are arranged in what is known as packages; a package being comprised of several steel laminations (seventy, in one example) stacked one atop the other. The packages are separated by the radially oriented inside spacer blocks, which, along with adjacent laminations of adjacent packages, define the radial ventilation ducts.
The fluid flow within the core lamination packages removes ohmic losses and magnetic losses by convective heat transfer. Those practitioners possessing ordinary levels of skill in the art will recognize this configuration as common, and will additionally recognize this flow to be turbulent in the fluid-dynamic sense in the tooth (radially inner) region of the duct. The inventors are also not aware of any previous effort to augment heat transfer in the stator core duct by means of a turbulence-enhancing or surface-area-enhancing devices. The inventors are not aware of any other application of turbulators to the stators of turboalternators; although the use of turbulators to increase the cooling rates within the interior flow passages of aircraft jet engine turbine blades is known.